The electromagnetic environment is becoming increasingly dense with the proliferation of wireless personal communication devices, such as cellular phones and pagers. Ever more information and sophistication are required from wireless communication systems, placing greater demands on antenna performance. Digital beam forming is a powerful technique for augmenting antenna performance.
The basic principles of digital beam forming have been described in literature. See for example, "Digital Beam forming Antennas An Introduction", by Hans Steyskal, Microwave Journal, January 1987. Generally, a digital beamformer operates in conjunction with a phase-array antenna to enhance the overall quality of radiated data signals. In a receiver, a radiated wave front impinging on an array antenna causes signals received at various antenna elements to differ in phase due to the angle of the wave front relative to the array. The digital beamformer compensates for this phase shift and sums together the different element signals such that maximum signal-to-noise ratio is obtained at its output. In the transmit direction, the beamformer's operation can be reversed, such that the transmitted signal can be made to travel in any desired direction by applying the appropriate phase shifts to each of the element signals.
Although a variety of techniques for beam forming have been developed, current digital beam forming antenna systems lack the computational performance required by many communication system applications. Consequently, there is a need for a digital beam forming system that provides high-performance computational power at low cost.